The present invention relates generally to optical scanning. Although specific reference is made to optical scanning in the context of an endoscope, the embodiments as disclosed herein will find applications in many fields such as optical displays, optical projectors, and imaging devices.
Prior methods and apparatus for scanning and displaying images can be less than ideal in at least some respects. Prior display devices such as image projectors and displays can be somewhat larger than would be ideal. Although scanning devices have been proposed, the prior scanning devices may have less than ideal image quality and can be somewhat larger than would be ideal.
Scanning devices can be used with minimally invasive medical procedures for various diagnostic and therapeutic applications so as to minimize tissue trauma, patient risk, and recovery time. During such procedures, the practitioner can visually inspect tissues within the patient's body using an endoscope. Conventional endoscopes may utilize a bundle of optical fibers to transmit light captured from an imaging plane to a detector outside the body. In some instances, the relatively large diameter of conventional endoscopes may preclude use in narrow passages and/or small spaces within the body. One significant improvement has been to decrease the diameter by reducing the number of optical fibers within the imaging bundle, for example with a scanning fiber endoscope.
Scanning optical fibers have been proposed in other fields in addition to endoscopy. However, the deficiencies of prior scanning optical fibers and can limit the utility and benefits of the prior scanning optical fiber devices, for example as used for imaging. Although prior scanning optical fiber imaging devices can decrease size, the prior scanning optical fiber scanners can be less than ideal. In some instances, the duty cycle and repeatability of prior scanning fiber devices may be less than ideal, which can be related to decreased image quality, increased power consumption and lower frame rates, for example. Additionally, the prior scanning fiber devices may be sensitive to changes in environmental conditions, such as temperature, and can be somewhat less robust than would be ideal. Also, as the fiber and actuator age, the resonant and deflection properties can change. Although the scanning fiber device can be recalibrated, the prior recalibration methods and apparatus can be somewhat less than ideal. Although position sensing optical detectors can be used to calibrate the fiber position of scanning fiber endoscopes, such calibration can somewhat cumbersome to use, and may not be well suited for use with at least some applications.
In light of the above, improved optical scanning devices are needed. Ideally such improved devices would be compact, capable of high resolution scanning and large display areas, provide quality images and measurements, capable of operating in many environments, and be well suited for use in many applications.